Cyclic acetals and production thereof



. acetals.

Patented June 24, 1941 UNITED STATES PATENT OFFICE 2.247.256 crcuc ACETALS AND raonuc'rron THE REOF

Murray Senkus, Terre Haute, Ind, assignor to Commercial Solvents CorporatiomTerre Haute,

1nd,, a corporation of Maryland No Drawing. Application April Serial No. 331,770

a claims. (or. 260-338) 'My invention relates to new and useful cyclic More particularly, it is concerned with -amino-L3-diox-anes having the following general structural formula:

wherein R may represent hydrogen, alkyl, or alpha-hydroxy-alkyl, and R may be either hydrogen, alykl, aryl, or furyl. As examples of the 5-amino-1,3-dioxanes which may be included within the scope of my invention, are the 2- phenyl-=5-amino-1,3-dioxanes, the 2-(3-heptyl)- 5-amino-1,3-dioxanes, and the 2-propyl-5-amino-l,3-dioxanes, which have the following structural formulas:

4 C-CH-CHzCHzCHzCHi R chum-o chum-0' H is active at temperatures as low as approximately C. and has an exceptionally long life.

The hydrogenation reaction in general may be efiected at hydrogen pressures ranging from atmospheric pressure to pressures slightly below those which tend to cleave the acetal linkage.

I have found it preferable, however, to carry out such reactions at a pressure of approximately 2000 pounds per square inch and at a temperature of about 25 (1., in the presence of thorough agitation. The rate of reaction is directly proportional to the temperatures and pressures utilized and therefore, if a lower pressure is desired, a correspondingly higher temperature must be employed. Lower temperatures and pressures will ordinarily require a longer reaction time and, conversely, higher pressures and temperatures will in general shorten the time for completion: of the reaction. However, under the latter conditions excessive pressures and/or temperatures, even with a short reaction period,

1 tend to result in lower yields of the desired wherein B may representhydrogen, alkyl, or

alpha -hydroxy-alkyl. and It may be either hydrogen, alkyl, aryl, or fury].

' The 5-amino-L3-didxanes of my invention may be prepared by any procedure which provides conditions that are favorable to acetal formation such as, for example, by reacting the desired aldehyde with an amino-polyhydroxy compound in the presence of a suitable catalyst. I prefer, however, to prepare these compounds by the catalytic hydrogenation of the The aluminum is dissolved out of the powdered alloy by strong alkali solution, and the remaining leached nickel residue is washed free from alkali and salts, with 'water and kept 'under liquid. The catalyst, produced in this manner,

' reactionrmixture by filtration and the solvent, (if employed, is distilled off. The 5-amino-1,3-

dioxanes, obtained in this manner are, in genamino compound. When carrying out the reaction'in accordance with the preferred conditions described above, the hydrogenation is in general found to be complete after a v period of from oneto two. hours. Optimum conditions in regard to the temperature, pressure, and catalyst, inany given instance, however, may be readily determined by simple experiment. Also, it is generally desirable to employ a suit-' able solvent such as methyl or ethyl alcohols.

After thereaction is complete, as may be evidenced by the failure of additional hydrogen absorption, the catalyst is separated from the eral, relatively pure products. However, if itiis desired to purify these materials further, if solids at ordinary temperatures, they may be recrystallized readily from the common organic solvents, such as acetone, ether, benzene, and the like. The products which are liquids at ordinary temperatures may be purified further by distillation under reduced pressure. The 5-nitro-1 ,3-dioxanes"employed in the preparation of these compounds, may be produced in accordance with any suitable procedure.

However, I prefer to prepare such compounds in accordance with the process described in mycopending application, Serial No. 331,769 filed April 26,1940. According to this process approximate 1y equivalent amounts of the polyhydroxy nitro compound and the desired aldehyde are-heated in the presence of a small amount of an acid catalyst, such as hydrochloric acid and, if. desired, in the'presence of. an organic liquid such as benzene or toluene,- which is capable of removing the water produced during the reaction,

v ture was withdrawn from the hydrogenation apin the form of a constant boiling mixture. I have vention are either colorless liquids, or crystalline found this reaction to be very general'in charwhite crystalline solids, and have been found to acter, and may be effected between any aldehyde be soluble in water, methanol, acetone, ether, and

and a polyhydroxy compound of the type herein benzene. They are, in general, stable compounds,.

disclosed. Suitable aldehydes, which may be emsome of which are capable oi withstanding temployed in this reaction, are formaldehyde, acetperatures as high as 200 C., with only slight dealdehyde, butyraldehyde, heptaldehyde, 2-ethyl composition. The following data were deterhexanal, benzaldehyde, furfuraldehyde. and the mined for certain of the 5-amino-1,3-dioxanes like. As examples of polyhydroxy nitro com- I prepared asdescribed abovez' pounds which may be utilized, there may be mentioned tris-(hydroxymethyl) -nitromethane, Ta l I Nitrogen Neutral Melti com and point, e 0. Boiling polnt, 0. 817518 p (uncor- (uncorrected) Cale. Found Calc. Found 2130pyl-5-hydroxy-methyl-5-amino-l,3- 34 8.00 8.04 176.0 176.0

oxane. 2-propyl- 5-methyl-5-amino-l,3 dioxane" 197.3 (748 mm).-- -heptyl)-5-methyl-5-amino-l 3-dioxane 103-4 (2 mm.) 2-phenyl-5-methyl-5-amino-l, loxane 5-ethyl-5-amino-l,3-d.ioxane 181 (760 mm.)

2 nitro 1,3 propanediol, 2-propyl-2-nitro-L3- Since the number of preparations of each of propanediol, 2,8-dimethyl-5-nitro-4,6-nonanedithese compounds was limited, it is to be underol, 1,3-diphenyl-2-nitro-1,3-propanediol, 1,3-distood that, while the above properties given will furyl-2-nitro-1,3-propanediol, and the: like. be useful in identifying the compounds of my in-' My invention may be further illustrated by the vention, I do not desire to be restricted to prodfollowing specific examples: c having the exact properties listed- E l I a The 5-amino-1,3-dioxanes of my invention mmp e I have been found to be useful in the formulation One hundred fifteen parts of 2-propyl-5- hyof various coating compositions. They are likedroxy-methyl-fi-nitro-1,3-dioxane, 650 parts of wise useful as intermediates in the preparation methanol and 5 parts of nickel catalyst, prepared of numerous organic compounds. Other uses of as described above, were placed in a suitable hy- 3 these products will readily occur to those skilled drogenation apparatus and sealed. This solution in the art.

was then hydrogenated at a pressure of 2000 My invention now having been described, what pounds per square inch at 25 C., for a period of I claim is:

one hour with constant agitation. After absorp- 1. 5-amino-l,3-dioxanes having the structural tion of hydrogen had ceased, the reaction mix- 40 formula: v

n came-0 H paratus, the catalyst removed from the solution by filtration and the methanol separated from the reaction mixture by means of fractional I distillation. The 2-propyl-5-hydroxymethyl-5- wherein R is a member of the class consisting of amino-1,3-dioxane thus obtained amounted to 95 hydrogen, fl y and p y y R1 18 parts, corresponding to .a 96% yield and was submember of the Class consisting of hydrogen, y stantially free from impurities. Further purifi- 'y and fury!- cation was effected, however, by recrystallizing -84 0- ,3 0 neS 0f e or ula once from ether. The crystalline product ob- I tained in this manner melted at 34 (uncor- H rected). I c c Example II 2-phenyl-S-methyl-S-amino- 1,3 dioxane was p pared by dissolv g 131 Parts Of -D e Yl-5- whereinR is a member of the class consisting of m t y1- '0- in 700 parts of methhydrogen, alkyl, and alpha-hydroxyalkyl, and R This Solution was then y genated unis a member of the class consisting of hydrogen.

der conditions similar to those described in Exalkyl, aryl, and furyl.

ample I in the P e of 7 parts of el cata- 3. S-amino-LS-dioxancs of the formula:

lyst. The corresponding amino compound was R CHWFO H obtained in 96% yield and melted at 82 0. (un- I corrected) after one crystallization from ether. 2 2C =OH= Example NH: CH(R)0 (31115 One hundred and twentwfour arts of wherein R is a member of the class consisting of heptyl) -5-methyl-5-nitro-1,3-dioxsfne was dishydmgem alkyl and aIPha'hYdrPXYaIKVI- and R1 solved in 700 parts of methano'l and the resulting is a member of the class consisting or hydrogen solution subjected to hydrogenation in the presalkyl, my], and furylence of 7 parts of nickel catalyst, according to 5'ammo'll3'dmxanes 0f the formula! the procedure outlined in Example I. There- 7 P. H H

suiting product, 2-(3-heptyl) -5-methyl-5-amino- 1,3-dioxane, distilled at 100104 C. (2 mm.), and

amounted tr 94 parts, corresponding to a yield (mum-0 of 86%. wherein R is a member of the class consisting of The 5-amino-1,3-dioxanes of the present inhydrogen, alkyl, and alpha-hydroxyalkyl, and R 2,247,256 Q is a member of the class consisting of hydrogen, -ni ro-L -di n to e orr e 5- alkyl, aryl, and furyl. a amino-1,3-dioxanes, the step which comprises 5. 2-propy1-5-hydroxymethy1-5-am1no-1,3 disubjecting a 5-nitro-L3-dioxane to hydrogenation oxane. in the liquid phase in the presence of a, hydro- 6. 2-pheny1-5-methy1 5-am1n0-1,3-d1oxane. 5 genation catalyst at a temperature below 125 C. '7. 2-(3-hepty1)-5-methy1-5-amino-1,3-dioxane; 8. In a. pl ocess for the direct hydrogenation of MURRAY SENKUS. 

